This invention relates to conveyor systems for moving can end parts, namely shells, through end conversion apparatus wherein the shells are scored, sometimes embossed, and have an operating tab secured in position with respect to a separable pouring panel.
Several forms of conveying systems have been, and presently are, used in conversion presses to carry shells through and between tooling stages at which operations are performed on the shells. A rotary tooling system was widely used in the beginning of the manufacturing of easy-open ends. Such system was supplied with tabs made on different equipment and fed into the rotary tooling from a magazine type supply. Those systems are presently considered as outdated, and those which remain are devoted to converting some specialty ends. A nest device used in the rotary system has three movable fingers to hold the end essentially in the nest center. In reality the two strongest springs overcome the weakest and hold the end against that outside diameter, actually off center. The nest end location with respect to the tooling stations around the rotatable table, and more critically between stations, is controlled by the condition of an indexing gear box.
Some conversion systems, principally used for specialty ends, employ a transfer bar type of mechanism for moving the parts though the stations of the end conversion tooling. A typical example is shown in U.S. Pat. No. 3,999,495. These are generally considered as relatively slow in operation.
Continuous conveyor belts predominate in the types of end conversion equipment presently marketed. Such continuous belts are presently the choice for several systems designed for the large volume beer/beverage type of ends. U.S. Pat. No. 3,812,953 shows a typical rubber/fabric type of belt, and U.S. Pat. No. 5,158,410 shows a typical metal (usually stainless steel) type of belt. Such continuous belts do operate at higher speeds, but they generally utilize a vacuum system to hold the ends in place in openings in the belts as these parts travel through the tooling; this usually produces an additional load on the belt drive, and tends to collect dirt which poses another impediment. Furthermore, there have been ongoing problems involving poor belt life, difficulties in forming a splice when such belts are replaced, or threading a continuous belt about drive and take-up drums and through the tooling as part of the belt replacement process.
Thus, vacuum hold-down systems for keeping shells in position in holes of a belt (as in the prior art) have been found to be expensive and dirty, and to impose an extra load on the belt movement which requires extra torque from the belt drive and additional wear along the belt. The elimination of vacuum hold-down systems along the belt through the various stations of tooling will provide a cost savings both in construction operation and in later maintenance.
Another problem has arisen from the need to keep round shells from rotating in the end carrying holes in the belts. U.S. Pat. Nos. 4,799,846 and 4,946,208 disclose efforts to avoid such turning of the shells and/or ends. Namely U.S. Pat. No. 4,799,846 discloses end shell carriers fitted to a continuous belt, and U.S. Pat. No. 4,946,028 discloses roughened rims surrounding the shell-receiving opening, in a continuous belt. Thus, it has been recognized that turned ends between work stations have been a long time cause of spoiled ends. A system which will positively retain the ends against rotation, without vacuum, is highly desirable.
U.S. Pat. No. 3,196,817 discloses a multi-carrier conveyor system, one of which was designed and operated for some time about forty years ago. The individual carriers are attached to a pair or conveyor chains which are advanced intermittently to move the carriers along the tooling stations of the end conversion tooling, in synchronism with sets of reciprocating press rams/platens which close and open the tooling at the successive stations. A lost motion type of connection between the carriers and the chains allows for substantial relative motion of the carriers, into and out of receptors which locate the carriers (and thus the shells and/or ends) relative to the upper and lower tooling. Such connections inherently introduce play in the fore/aft connections by which the chains advance the carriers, thus slowing the operation and placing additional centering responsibility on the receptors for consistent proper alignment of the shells and ends with respect to the tooling at each station. This system used spring finger for retaining parts in the carriers, similar to the retainers used in the aforementioned rotary systems.
The transfer conveyor system of the present invention utilizes a conveyor comprising at least one continuous belt of reinforced flexible rubber-like material, with cogs or teeth on its underside and with a series of nests which fit into holes in the belt. The nests are attached at their opposite edges to the positively driven, intermittently advancing, belt.
The belt is supported by and routed around an idler drum, located outside the press frame posts next to a down-stacker mechanism, and a drive drum located within the press frame adjacent the opposite frame posts. The progressive end conversion tooling for making shells into completed easy-open can ends is located between the posts along (above and below) the upper and lower tooling sets. The tab making tooling is preferably located between the drive drum and the other frame posts, and the carrying strip of formed tabs is routed back to the main tooling station where the tabs are applied to the ends. The drive drum and idler drum are provided with circumferential tooth configurations which form a positive drive to the belt. The press includes power take-off mechanisms which drive and synchronize the shell feeding, tab strip feeding, and other mechanisms.
The attachments between the nests and belt are located on transverse center lines (perpendicular to the path of belt travel), which attachments permit the generally flat and rigid nests to travel around the end turns of the belts, and to carry the parts within the nests about this turn. These attachments thus allow for limited and controlled relative movement between the nests and the belt, only in directions parallel to the plane of motion of the belts, but not in directions perpendicular (up and down) with respect to the belt upper surface.
The active (upper) flight of the belt is lifted and moved incrementally forward when the press is opened, to locate the nests successively in alignment with progressive stations of can end conversion tooling. The flight is then lowered to locate the nests onto the lower tooling aligned precisely with respect to the tooling before it closes. Each nest comprises a positive holding device in the form of a circular array of flexible fingers in a nest ring, which array engages shells firmly at their periphery and inhibits the shells from rotating or shifting between operations. In a typical embodiment of the invention, there are plurality of nests in each of two to four lanes along the belt or belts. Shells are rotary down-stacked or loaded into the nests near the beginning of the active flight of the conveyor belt.
The shells are positively seated into the nests by applied differential air pressure, and then are mechanically positively seated into and firmly held by the circular array of independent stepped fingers as the nests are transferred through the conversion tooling. After conversion the completed ends are carried around the drum at the end of the upper flight, and the ends are ejected from the nest rings and moved [as by force from air streams] along a table or chutes to conveyers familiar in end making facilities. These chutes thus receive the ends from the lower or return flight of the conveyor, providing a compact (end-to-end) conveying system.
Also, this new belt transfer system, preferably but not necesarily usung multiple belts, lends itself to easier end size changes and even to running different sizes of ends in each lane. This is readily accomplished by attaching nests of different sizes in different ones of the lanes.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.